1.Field of the Invention
The present invention concerns a variable-size induction heating plate, and an induction cooking surface integrating such a plate.
2. Description of the Related Art
The present invention applies generally to the field of domestic induction cooking appliances, such as induction vitroceramic cooking surfaces.
An induction heating plate generally consists of a circular winding adapted to the dimension of a cooking vessel of given size.
It can equally consist of a plurality of concentric windings enabling adaptation to different diameters of vessels disposed on the cooking surface above the plate.
A heating plate can equally consist of a plurality of windings disposed side by side and supplied with power by independent generators, as described in patent application FR 2 758 994.
Also known are cooking surfaces comprising a plurality of small windings disposed in a cooking surface. One such cooking surface is described in the document FR 2 863 039 in particular. That document describes a set of circular windings disposed side by side so as to cover all of the area of the cooking surface. In this kind of set, the windings are magnetically independent and are controlled independently so that each heating plate is determined individually as a function of the position of the vessel on the cooking surface, facing the windings.
However, as a function of the position of the vessel on the cooking surface, it is not rare for a significant proportion of a group of windings not to be covered by the vessel, with the result that the power delivered by the induction winding is low.
The power delivered, by a particular heating plate depends on the electromagnetic matching between the induction winding and the vessel disposed above it. The vessel is seen as a resistive load by the current generator feeding the induction winding. In principle, induction heating devices are designed to optimize the electromagnetic matching and to maximize the power delivered when the vessel completely covers the area of the induction winding.